Effects of variations in hydrological connectivity on the macrobenthic community structure in reclaimed wetlands

The Nanhui Dongtan Wetland is the most extensively reclaimed part of the Yangtze River Estuary wetland. In recent decades, urbanization has led to the extensive reclamation of the intertidal wetlands of Nanhui Dongtan. Macrobenthos are crucial as secondary production groups in the food web. However, there is a lack of in-depth research on the response mechanisms of macrobenthic communities to environmental disturbances in reclaimed wetlands. This study investigated the impact of hydrological connectivity changes caused by land reclamation on the macrobenthic community based on the macrobenthic community composition in preserved tidal flats and closed and open reclamation areas in Nanhui Dongtan. The results showed that the macrobenthos species richness in the closed reclamation area was significantly lower than that in the other areas. After dividing the functional groups of macrobenthos, structural equation modeling revealed a negative correlation between the salinity and the functional group composition. Analysis of the food sources revealed significant positive correlations between predatory and sediment-feeding populations and sediment organic matter content, between detritivorous group and environmental chlorophyll-a content, and between herbivorous group and suspended organic matter content in water. Therefore, variations in hydrological connectivity in different reclamation areas caused differences in food source distribution, which led to different compositions of macrobenthic functional groups. The results of this study provide a theoretical reference for the study of intertidal wetland habitat restoration.